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Review: Kingston UHS-I U3 64GB SDXC Card (As it Applies to a DSLR)

I recently(ish) got a higher performance DSLR camera (the Canon 70D), complete with 7FPS shooting capability. One thing that can impact overall FPS, especially is a faster memory card. Previously, the only higher capacity cards I had were 16 GB Class 6 cards, so when Kingston emailed about their new UHS-3 cards, I couldn't resist and jumped on the opportunity to review one. They kindly sent along a 64 GB UHS-I speed class 3 (U3) rated SDXC card.

Rated for a very speedy 80 MB/s write and 90 MB/s read, these cards are billed as being built for 4K Ultra-HD video capture, but they will also help when using SLRs with fast burst speed, which also have to write tremendous amounts of data in short periods. You can see the detailed specifications on Kingston's site.

As I didn't have a USB 3.0 card reader, and because Kingston is nice like that, they also sent along a media card reader so this thing could be tested not only in the camera, but when transferring files to a computer.

It's supremely easy to work. With WindowsXP firmly in the past, all you need to do is plug it in via the included cable and it's instantly recognized as a multiple-drive device. That does clutter up your computer drive display a bit with quite a few new 'drives', but that's typical of any card reader, both internal or external.

Today's competition comes courtesy a Transcend 16 GB Class 6 SDHC card that has served us well for several years now.

The Transcend card did allow the camera to burst at its full ~7 FPS in all modes (JPEG, RAW & RAW+JPEG), but the buffer always took a long time to clear and after the buffer was full, the burst speed dropped precipitously, to an abysmal 0.5 FPS.

The Kingston card surprisingly didn't add very much to the buffer fill time at all. It increased but not by much.

The two things that DID improve significantly were "FPS after buffer fill" (while the camera is frantically trying to write to the SD card and clear the buffer) and the 'time to clear buffer' metrics.

Yes, you read that right. It takes under one second (so fast I couldn't pretend to accurately measure) to clear the buffer in Fine JPEG mode. While it takes longer to clear RAW and RAW+JPEG buffers, time to clear RAW was measurably less and time to clear RAW+JPEG was cut nearly in half.

The "FPS after buffer fill" also increased substantially, by over three TIMES when shooting RAW only. Though still just under 2 FPS, it's a lot better than half an FPS.

Now we'll put the two side-by-side and you can see how they compare directly.

Of course, another big advantage to much faster SD cards is transfer speeds, so you can get to work sifting through (and post processing) your photos that much faster.

To measure transfer speed, I used CrystalDiskMark and ATTO Disk Benchmark.

*Note I made a mistake in the text running these benchmarks. The Kingston card is not UHS-3, which does not exist. It's UHS-I U3.

On average, the Kingston card is rated right where it should be. In ATTO, write speeds were just short of the rating but CrystalDiskMark shows writes exceeding the rated 80 MB/s. Both benchmarks show the card exceeding the rated 90 MB/s by a solid 6 MB/s.

The last thing to talk about is price. UHS-I Class 3 cards aren't as cheap as you may be used to in SD cards. The Kingston UHS-I U3 64 GB card, model # SDA3/64GB, runs $108.80 shipped from Newegg. The 32 GB card is a more palatable $57.71 shipped and 16 GB will run you $40.25 shipped. As any early-adopter knows, that kind of markup is what you pay for the newest, fastest hardware.

I'm not here to tell you whether it is worth it for you to buy an ultra fast SD card, but I am here to show you that if you do, Kingston's new UHS-I Speed Class 3 cards will perform right where they says they will, and they will make your ability to get the shot that much stronger - not to mention get you imported and editing that much faster.

Thanks to Kingston for sending this card for evaluation. I'm happy to answer any questions that anyone has and run additional tests if you would like; just ask!

I don't understand that at all, frankly. I ran it multiple times to make sure I didn't get it wrong, but that's how it performed. Here's my theory:

I think what happens is that it's capable of writing several more RAW to the card while shooting because it doesn't have to process them at all; it is funneling them from the sensor to the card as fast as it can, which keeps the buffer from filling up as quickly.

The JPEGs get stuck in the buffer while it's processing and if it waits to move the RAW while it's processing, it will fill up quickly. Thus, I think it's reasonable to assume the RAW+JPEG stops when the buffer is full, where RAW continues on because it's able to off-load some onto the card.

So, using that assumption, we can gather that the buffer is about 192 MB (9 RAW + 9 JPEG = 185 MB, the next logical step in MB terms is 192 MB, assuming normal chip sizes.

Hmm, interesting 'bottleneck'. I wonder if it is a firmware bottleneck so that you might not fill the buffer. Canon might have wanted to make the buffer conservatively small in case for heavy-processing on JPGs (high level of noise reduction on high ISOs should take longer to process). I dunno, I'm taking a guess. FWIW, my 6D claims a buffer for 10 RAW shots, and 6 for RAW+JPG.

Anyway, if 20 RAW shots can fill the buffer, I would estimate the buffer to be 384MB, and the theoretical write speed of the 70D SD slot is 40MB/s (based on 19,000KB * 20 frames / 9.12 seconds). I think I read somewhere that the 6D has a similar write speed, so I would guess they share a similar slot/firmware. A little disappointing, since there are SD cards that write much faster than that (I heard Kingston has a fast card ). I wonder if they crippling the current SD card slots and will release a faster one for the 7D2??